Re: [PATCH v4 6/7] sched/deadline: Deferrable dl server

[Peter Zijlstra]

On Wed, Sep 06, 2023 at 04:58:11PM +0200, Daniel Bristot de Oliveira wrote:

> > So one thing we could do is have update_curr_fair() decrement
> > fair_server's runtime and yield the period then it hits 0 (and capping
> > it at 0, not allowing it to go negative or so).
> > 
> > That way you only force the situation when FAIR hasn't had it's allotted
> > time this perio, and only for as much as to make up for the time it
> > lacks.
> 
> We can also decrease the runtime to a negative number while in
> defer/throttle state, and let the while in replenish_dl_entity() to
> replenish with the += runtime;

Yes, but my point was that fair_server gives a lower bound of runtime
per period, more -- if available -- is fine.

If we allow negative runtime, you'll affect future periods, and that is
not desired in this case.

Or am I still confused?